1. Field of the Invention
The present invention relates to an all terrain vehicle for traveling on uneven ground such as wasteland, grassland, and swamps. More particularly, the present invention relates to technology for a vehicle wheel suspension for a four-wheel drive vehicle.
2. Description of the Related Art
In an all terrain vehicle including independent suspensions that suspend left and right front wheels, so-called double wishbone type suspensions are sometimes provided. A double wishbone type suspension is a suspension having a lower arm and an upper arm arranged above the lower arm for suspending a front wheel. These lower arm and upper arms are formed in a V-shape.
Generally, a two-wheel drive all terrain vehicle driven only by rear wheels and provided with a type double wishbone type suspension for the front wheels includes shock absorbers connected to the lower arms (refer, for example, to Japanese Patent No. 2610268).
Specifically, body portions (telescopic portions) of the shock absorbers are arranged at an inner side of the V-shaped upper arms, between front arm portions and back arm portions. Upper ends of the shock absorbers are connected to a vehicle frame, and lower ends of the shock absorbers are connected to the lower arms.
If the shock absorbers are connected to the lower arms in this way, the center of gravity of the vehicle is low compared to when connected to the upper arms. Therefore, a comfortable ride is possible even if the vehicle is traveling over uneven ground.
However, in a four wheel drive all terrain vehicle provided with double wishbone type suspensions, it is difficult to connect the lower ends of the shock absorbers to the lower arms in a similar manner to the above described two-wheel drive vehicle.
That is, a four wheel drive all terrain vehicle includes front wheel drive shafts connecting the front wheels and a differential unit, and the drive shafts are arranged between the lower arms and the upper arms. As a result, the drive shafts obstruct the arrangement of the shock absorbers, and the lower ends of the shock absorbers cannot connect to the lower arms. If the body portions (telescopic portions) of the shock absorbers are positioned in front of or behind the drive shafts, and the lower ends of the shock absorbers are connected to the lower arms so as to avoid the drive shafts, the upper ends of the shock absorbers are likely to contact the upper arms when traveling.
To deal with this, for example, it has been considered as a solution to widen a distance between the front arm portions and the back arm portions of the upper arms in order to remove the danger of the upper portion of the shock absorbers contacting the upper arms. However, with this approach, in order to support the upper arms using the vehicle frame, it becomes necessary to extend the front of the vehicle frame forward. If this is done, when the vehicle moves up and down when traveling on uneven ground, there is a danger that a front lower portion of the vehicle will contact the ground.